As an American kid born along with the digital epoch of the 90s, I'm a bit of an oddity because the only social media I've ever used (& still use) is LinkedIn, which feels like sharing a room with a vipor. I have it set up with a dedicated email address and I only interact w/it in a sandboxed browser on VPN with a dedicated email address. (I guess you could add HN, StackExchange and GitHub to the list since there are…
FWIW, some do. The only reason I signed up for Facebook was to have an asynchronous medium in which people can "contact" me, instead of trying to meet up, call my phone, text me, etc. I use Google+ for sharing photos/updates with my family while I travel, and LinkedIn for recruiter fishing. I use each of the above at least a few times a week, but always out of necessity; I've set a pretty solid standard of "I may take a couple weeks to respond, but I'll always respond" which is so much nicer than being constantly interrupted by people reaching out through direct means.
Email was nice for this originally, but there's way less friction to contacting someone through FB than there is through email, and keeping social messages out of email keeps my inbox more manageable for productive uses without having to set up and maintain filters.
Of course, YMMV. But just remember not everyone likes/minds the same things. :)